Electric Heating Systems and Associated Methods

ABSTRACT

Electric heating systems and associated methods that circulate a heating medium (e.g., antifreeze) and may comprise a tank, a pump, a motor blower, and/or a heater core. In certain applications, the electric heating systems may be used to heat the floor of a farm enclosure, such as the ground of a poultry house.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent application Ser. No. 12/627,806, entitled “Electric Heating Systems and Associated Methods,” filed on Nov. 30, 2009, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure generally relates to electric heating systems. In particular, in one or more embodiments, the present disclosure relates to electric heating systems and associated methods of heating that circulate a heating medium (e.g., antifreeze) and may comprise a tank, a pump, a motor blower, and/or a heater core.

A variety of different heating systems have been used heretofore for both central heating and space heating. In a typical central heating system, the system generates heat at a single location and then distributes that heat to the interior of a building. Such systems may be used in private homes, public buildings, and commercial buildings. Central heating systems may be combined with other systems that provide ventilation and air conditioning to a building. These combined heating, ventilating, and air conditioning systems are commonly referred to by the acronym “HVAC.” Fossil fuels, electricity, solar energy, and heat pumps may be used to provide the heat needed in a central heating system. This heat may be distributed through the house by heating a fluid (e.g., air, steam, water) that is circulated through the building. By way of example, a duct system may be used to distribute heated air through a building. By way of further example, pipes may be used to distribute heated water/steam through a building to radiators that transfer the heat from the heated water/steam to the building's air. Drawbacks to these conventional heating systems may include energy consumption, as well as environmental hazards, such as potentially undesirable levels of oxygen consumption.

One particular area of interest for heating systems is in the poultry industry. Heating systems are particularly important for broilers (e.g., chickens raised for meat production). Broilers typically do not provide sufficient heat to maintain proper house temperatures. During the first three weeks of their lives, the broilers may be particularly susceptible to temperature changes with lower than desired temperatures having potentially negative impacts on the chickens' development. Accordingly, it is important for the temperature in the poultry house to be maintained at a constant level during the grow-out period. Maintaining constant temperature in the poultry house can also be important for breeders; however, breeders are typically of a larger size so they can provide at least some of the heat necessary to maintain the desired house temperature.

Poultry growers typically burn fossil fuels, such as propane or natural gas, to heat the poultry houses. However, as would be expected, heat generally rises with warm air collecting at the ceiling and cool air collecting around the birds. In addition, the ground temperature in the houses typically remains at a constant level during summer and winter with the fossil fuels not bringing up the ground temperature. To insulate the birds from the cold ground, growers commonly place wood chips on the ground to serve as a barrier between the birds and the cold ground. Despite these efforts, purchasing fossil fuel remains a significant expense in the growing of birds.

Thus, there is a need for improved heating systems that can be used for central heating, space heating, and/or ground heating.

SUMMARY

An embodiment of the present invention provides an electric heating system for heating a floor of a farm enclosure. The electric heating system may comprise a tank for storing a heating medium. The electric heating system further may comprise an electric heating element disposed in the tank for heating the heating medium in the tank. The electric heating system further may comprise a pump for circulating the heating medium in the electric heating system. The electric heating system further may comprise conduit fluidly connecting the pump and the tank, wherein at least a substantial portion of the conduit is located beneath a top surface of the floor.

Another embodiment of the present invention provides an electric heating system for heating a dirt floor of a poultry house. The electric heating system may comprise a tank containing a heating medium comprising antifreeze. The electric heating system further may comprise an electric heating element disposed in the tank for heating the heating medium in the tank. The electric heating system further may comprise a pump for circulating the heating medium in the electric heating system. The electric heating system further may comprise conduit fluidly connecting the pump and the tank. The conduit may comprise a buried portion that is in ground beneath a top surface of the dirt floor. The conduit may comprise a material having a thermal conductivity at 25° C. of greater than or equal to 10 W/(m° C.).

Another embodiment of the present invention provides a method of heating a floor of a farm enclosure. The method may comprise heating a liquid in a tank with an electric heating element, wherein the liquid comprises antifreeze. The method further may comprise circulating the liquid beneath a top surface of the floor such that the liquid heats the floor. The method further may comprise returning the liquid to the tank.

The features and advantages of the present invention will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of the present invention and should not be used to limit or define the invention.

FIG. 1 is a schematic illustrating the various components of an electric heating system in accordance with one embodiment of the present invention.

FIG. 2 is a schematic illustrating the various components of an electric heating system in accordance with one embodiment of the present invention.

FIG. 3 is a schematic illustrating a tank and its various components in accordance with one embodiment of the present invention.

FIG. 4 is a schematic illustrating the relationship between the blower and the tank in accordance with one embodiment of the present invention.

FIG. 5 is a schematic illustrating incorporation of a heater core into a duct system in accordance with one embodiment of the present invention.

FIG. 6 is a schematic illustrating the various components of a ground heating system in accordance with one embodiment of the present invention.

FIG. 7 is a top view of a tank and its various components in accordance with one embodiment of the present invention.

FIG. 8 is an end view of a tank and its various components in accordance with one embodiment of the present invention.

FIG. 9 is a schematic illustrating use of ground heating systems in a farm enclosure in accordance with one embodiment of the present invention.

FIG. 10 is a schematic illustrating a test apparatus in accordance with one embodiment of the present invention.

FIG. 11 is a depth profile for the test apparatus of FIG. 10 in accordance with one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure generally relates to electric heating systems. In particular, in one or more embodiments, the present disclosure relates to electric heating systems and associated methods of heating that circulate a heating medium (e.g., antifreeze) and may comprise a tank, a pump, a motor blower, and/or a heater core. In accordance with embodiments of the present invention, the electric heating system may be used for central heating, space heating, or any other suitable heating purpose. For example, the electric heating system may used in a central heating system to provide heat for a private home, public building, or commercial building. By way of further example, the electric heating system may be used locally to provide heat to a space, such as a room, warehouse, or the like. In one embodiment, the heating systems may be used to heat the ground in a farm enclosure, such as a poultry house.

There may be several potential advantages to the systems and methods of the present invention, only some of which may be alluded to herein. One of the many potential advantages of the systems and methods of the present invention is that the embodiments of the electric heating systems of the present invention may utilize less energy than conventional heating systems, whether the conventional systems rely on electricity, heating oil, propane, or the like to provide energy. For example, embodiments of the present invention may utilize up to six times less energy than a conventional electric heater. Another potential advantage of the systems and methods of the present invention may be reduced environmental hazards, in that embodiments of the present invention may consume less (or potentially no) oxygen when compared to conventional heating systems. Yet another potential advantage may be that embodiments of the present invention may have reduced risk of fire as compared to heating systems, for example, that rely on fossil fuels for energy. Yet another potential advantage may be that embodiments of the present invention may be used to heat the ground in poultry houses allowing the maintenance of constant house temperature with the potential for lower heating costs.

FIGS. 1 and 2 illustrate an electric heating system 10 in accordance with one embodiment of the present invention. FIG. 2 is a top schematic view illustrating the general arrangement of the various components of the electric heating system 10. As illustrated, the electric heating system 10 may include tank 20 for storing a heating medium, pump 30 for circulating the heating medium, heater core 40 for exchanging heat between the heating medium and air, and motor blower 50 for forcing air across the heater core 40. Cover 60 may also be provided for enclosing the system 10. In the illustrated embodiment, the heating medium (e.g., antifreeze) may be heated to a desired temperature in the tank 20. A heating medium feed 70 may carry the heating medium from the tank 20 to the heater core 40 by way of the pump 30. A heating medium return 80 may then carry the heating medium back to the tank 20. In the heater core 40, heat may be transferred from the heating medium to the air that may be forced across the heater core 40 by the motor blower 50. The heated air may then be distributed as desired for a particular application. In certain embodiments, a duct system may be used to distribute the heated air through a home or building, such as when the system 10 is used for central heating.

Referring now to FIG. 3, the tank 20 is illustrated in more detail in accordance with one embodiment of the present invention. As illustrated, the tank 20 may include a heating medium return 80 and a heating medium outlet 90. The heating medium may be drawn from the tank 20 via the heating medium outlet 90 and returned to the tank 20, after circulation through the heater core 40, via the heating medium return 80. In certain embodiments, the tank 20 may be raised a short distance from the base of the cover 60. Additionally, in certain embodiments, the tank 20 may not be insulated such that heat is lost from the tank 20. At least a portion of the heat lost from the tank 20 may be recovered by the motor blower 50, thus increasing the efficiency of the motor blower 50. By way of example, passive heat loss from the tank 20 may heat surrounding air that is then drawn into the motor blower 50. In this manner, the motor blower 50 intakes air that is hotter than ambient room temperature. In addition, passive heat loss from the tank 20 may also serve as a space heater, heating the room in which the system 10 is located.

Any of a variety of suitable materials may be used to construct the tank 20. Examples of suitable metals include black iron, cast iron, and aluminum. Black iron generally refers to a type of metal constructed from steel that is not galvanized. Black iron tanks may be preferred in certain applications due to their improved heat absorption, for example, as compared with galvanized metals. Improved heat absorption may be preferred, in certain embodiments, to provide increased passive heat loss from the tank 20. Passive heat loss from the tank 20 may be captured, for example, in air that is drawn into the motor blower 50 and/or in a metal strap (as discussed below) that may connect the tank 20 and the motor blower 50. In accordance with embodiments of the present invention, the tank 20 may constructed from a material comprising black iron and having a thickness of about ⅛ inch.

The tank 20 may be of any general shape, including, for example, rectangular, square, cylindrical, oval, and a variety of other shapes that may be suitable for a particular application. In certain embodiments, the tank 20 may be a horizontal rectangular tank. Rectangular tanks may be desired in certain applications due to their ease of construction, cost, and passive heat loss, as compared to cylindrical tanks. As mentioned above, passive heat loss from the tank 20 may be desired in certain applications. The tank 20 generally should be sized based a number of factors, including the volume of the heating medium needed to provide the desired heat generation. In one particular embodiment, the tank 20 may be about 15 inches in length, about 8 inches in width, and about 14 inches in height.

A heating medium for circulation in the electric heating system 10 may be stored in the tank 20. As illustrated by FIGS. 1 and 2, the heating medium may be circulated in the system 10 in a closed loop in accordance with one embodiment of the present invention. As will be discussed in more detail below, a heating element 100 may be located in the tank 20 for heating the heating medium to a desired temperature. A wide variety of liquids may be suitable for use as the heating medium. Examples of suitable liquids include water, antifreeze, cooking oil, and motor oil. Combinations of suitable liquids may also be suitable. By way of example, one suitable heating medium includes a mixture of water and antifreeze. Ethylene glycol based antifreeze and propylene glycol based antifreeze should both be suitable for use in embodiments of the present invention. To reduce and/or eliminate loss of the heating medium due to evaporation, organic liquids (e.g., antifreeze) may be used in certain embodiments. Additionally, to reduce the risk of fire, antifreeze and/or water may be used in certain embodiments.

As illustrated by FIG. 3, the tank 20 may include a heating element 100, a temperature sensor 110, a thermostat 120, and a relief valve 130. As illustrated, the heating element 100 may be disposed through a side of the tank 20. By way of example, the heating element 100 may be disposed through a nipple that is welded in the side of the tank 20. The heating element 100, in certain embodiments, may be located about 5 inches from the bottom of the tank 20. In certain embodiments, the heating element 100 may be an electric immersion heater. In addition, the heating element 100 may deliver about 2,000 watts of heating output while using about 16.5 amps of power, in accordance with embodiments of the present invention. The heating element 100 may be used, for example, to heat the heating medium to a desired temperature. By way of example, the heating element 100 may heat the heating medium to a temperature of about 120° F. to about 150° F. If the heating element 100 is disconnected from the electricity, the heating medium may remain warm (e.g., above room temperature) for up to about 12 hours, for example. However, the heating element 100 generally should remain connected to an electrical outlet, in accordance with embodiments of the present invention. The tank 20 further may include a temperature sensor 110. The temperature sensor 110, for example, may also be disposed through the side of the tank 20. By way of example, the temperature sensor 110 may be disposed through a nipple that is welded in the side of the tank 20. As illustrated, the temperature sensor 110 may be located above the heating element 100. In certain embodiments, the heating element 100 may have an integrated temperature sensor.

The temperature of the heating medium in the tank 20 may be controlled, in certain embodiments, by the thermostat 120. In certain embodiments, the thermostat 120 may be a digital thermostat. The thermostat 120 may have, for example, a breaker. The thermostat 120 may be set to maintain the temperature of the heating medium at a desired temperature. In this manner, the thermostat 120 may turn off the heating element 100 when the heating medium in the tank 20 reaches or exceeds the desired temperature. For example, the thermostat 120 may turn off the heating element 100 when the temperature of the heating medium reaches about 150° F. Controlling the temperature of the heating medium in the tank 20 is a safety measure that can be used to prevent overheating in the tank 20. As illustrated, the heating element 100 and the temperature sensor 110 may be coupled to the thermostat 120. In the illustrated embodiment, the thermostat 120 is coupled to the side of the tank 20. However, while the thermostat 120 is illustrated on the side of the tank 20, it should be understood that the thermostat 120 may be placed in any suitable location for controlling the temperature of the heating medium.

The relief valve 130 may be disposed in the top of the tank 20, in accordance with embodiments of the present invention. The relief valve 130 generally may serve as an additional safety feature for the electric heating system 10. While the thermostat 120 should control the temperature inside the tank 20, in certain embodiments, the relief valve 130 may be a temperature relief valve, opening to relieve excessive temperature that may be built up inside the tank 20. If there is any exhaust heat from the relief valve 130, this heat should remain within system 10 such that no heat loss occurs, maintaining the system's efficiency. Alternatively, the relief valve 130 may be a pressure relief valve 130, opening to relieve excessive pressure that may be built up inside the tank 20. In certain embodiments, the relief valve 130 may be a temperature/pressure relief valve. The temperature/pressure relief valve may be set to relieve excessive temperature and/or pressure inside the tank 20 if it approaches the limits of the tank 20. The relief valve 130 does not need to be permanently welded to the tank 20. By way of example, the relief valve 130 may be screwed into a nipple that is welded in the top of the tank 20. When needed, the relief valve 130 may be unscrewed for adding and/or replacing the heating medium in the tank 20, for example, during system maintenance.

Referring again to FIGS. 1 and 2, the pump 30 may circulate the heating medium in the electric heating system 10 in accordance with one embodiment of the present invention. As illustrated, the pump 30 draws the heating medium from the tank 20 and delivers it to the heater core 40 by way of the heating medium feed 70. The pump 30 may carry the heating medium from a lower level of the tank 20 to the higher level of the heater core 40. The pump 30 may be connected to the tank 20 via any suitable connection. By way of example, the pump 30 may be connected to the tank 20 by a ⅝ inch heater hose. In certain embodiments, the pump 30 may be modified to have threaded inlet and outlet connections. For example, the pump 30 may be threaded to fit a ⅜ inch adapter for the heater hose. A variety of different circulating pumps may be suitable for use in the electric heating system 10, in accordance with embodiments of the present invention. An example of a suitable circulating pump is Dayton Circulating Pump SM-303-BS, available from W.W. Grainger, Inc. The pump 30 may be rated to withstand the temperatures of the circulating heating medium. For example, the pump 30 may have a maximum temperature of 230° F. or greater.

As illustrated by FIGS. 1 and 2, electric heating system 10 further may include heater core 40. In accordance with embodiments of the present invention, the heater core 40 may be any suitable heat exchanger for exchanging heat from the heating medium with air from blower 50. In certain embodiments, the heater core 40 may be a tube-fin heat exchanger. In these embodiments, the heating medium may be passed through the tubes of the tube-fin heat exchanger while the motor blower 50 forces air across the tubes. The heater core 40 may comprise a number of different suitable materials, including, for example, copper. Heating medium feed 70 may provide the heating medium to the heater core 40. The heating medium may be returned to the tank 20 by heating medium return 80. Any of a variety of different connections may be suitable for connecting the heater core 40 to the pump 30 and the tank 20. In certain embodiments, a ⅝-inch nipple on the heater core 40 may be connected to the heating medium return 80, which may be a ⅝-inch heater hose. A ⅜-inch nipple on the heater core 40 may connect the heater core 40 to the heating medium feed 70 from the pump 30. While not illustrated, the heater core 40 may be covered, for example, by a square metal cover, for example, in embodiments where the system 10 is portable. As previously mentioned, the electric heating system 10 may be portable for a number of applications, including space heating. Alternatively, the heater core 40 may be connected to a duct. The heater core 40 may be connected to a duct for a number of applications, including central heating. By way of example, the heater core 40 may be connected in a duct of an HVAC system.

FIG. 4 illustrates the motor blower 50, in accordance with one embodiment of the present invention. As previously mentioned, the motor blower 50 may force air across the heater core 40 such that heat from the heating medium is transferred to the air. This heated air may then be used for central or space heating, for example. As illustrated, the motor blower 50 may include a centrifugal blower 140 connected to a blower inlet 150 and a blower outlet 160. Air from the blower outlet 160 may be directed across the heater core 40. The motor blower further may include a motor 170, which may be connected to an appropriate electric power supply. To provide improved efficiencies in the electric heating system 10, the blower inlet 150 may be spaced a distance D from a side of the tank 20. By way of example, the blower inlet 150 may be a distance D of about ½ inch to about 1½ inches from a side of the tank 20. In one embodiment, the blower inlet 150 may be a distance D of about 1 inch from the side of the tank 20. By locating the blower inlet 150 proximate to the tank 20, the motor blower 50 may intake air that has already been heated, capturing passive heat loss from the tank 20 and, thus, reducing the heat from the heating medium that is needed to provide the desired heat output from the system 10.

Referring again to FIG. 2, a metal strap 190 may be coupled to the tank 20 and the motor blower 50, in accordance with embodiments of the present invention. By way of example, the metal strap 190 may be welded to the top of the tank 20 and also coupled to the motor blower 50. The metal strap 190 may be bent, for example, to form an elbow that is attached to the motor blower 50. The metal strap 190 may function to stabilize the motor blower 50. In addition, the metal strap 190 may also transfer heat from the tank 20 to the motor blower 50, increasing the heat output from the motor blower 50. Capturing passive heat loss from the tank 20 with the metal strap 190 generally should reduce the heat from the heating medium that is needed to provide the desired heat output from the system 10.

The motor blower 50 may be controlled by blower thermostat 180, in accordance with embodiments of the present invention. The blower thermostat 180 may include, for example, a temperature sensor (not illustrated) for sensing the room temperature. The blower thermostat 180 may be set to turn on the motor blower 50 and, thus, the motor 170 at a specified temperature. Any of a variety of different motor blowers may be used in accordance with embodiments of the preset invention. An example of a suitable motor blower is Dayton High Temperature Blower 1TDV4, available from W.W. Grainger, Inc.

As previously mentioned, the electric heating system 10 may be enclosed by cover 60, such as a metal cover. In certain embodiments, the cover 60 may be an enclosure having four sides, a base, and a top. The cover 60 may be sized for enclosing the system 10. In certain embodiments, the cover 60 may be have a width of about 22 inches, a length of about 22 inches, and a height of about 16 inches. Optionally, wheels (e.g., 4 wheels) may be attached to the bottom of the cover 60, providing added mobility to the system 10. The cover 60 may include several openings as desired for particular applications. For example, the cover 60 may include an opening (e.g., a square opening) sized for the heater core 40. By way of further example, the cover 60 may include an opening (e.g., a circular opening) sized for the motor blower 50. The opening for the motor blower 50 may be provided to prevent and/or reduce overheating of the motor blower 50. By way of further example, there may also be an additional small vent opening in the cover 60 at the back of the motor blower 50.

A variety of suitable wiring configurations may be used for connecting the pump 30, the motor blower 50, the heating element 100, the thermostat 120, and the blower thermostat 180 to an electric power supply. Provided herein is a description of an example wiring configuration that may be used in accordance with one embodiment of the present technique. It should be understood that other suitable wiring configurations may also be used in accordance with embodiments of the present invention. The electric heating system 10 may be placed on a dedicated circuit with a separate breaker, for example, a 20-amp breaker. This circuit may be similar, for example, to a dedicated circuit that may be used for a residential washing machine. There may be a common on/off switch to control the supply of power to the system 10. The pump 30, the thermostat 120, and the blower thermostat 180 may each be separately wired to the power supply. The heating element 100 may be wired to the motor blower 50 with the motor blower 50 wired to the blower thermostat 180. In this manner, the blower thermostat 180 may help to control the temperature of the heating medium. In other words, the blower thermostat 180 may be set to turn on the motor blower 50 when the room temperature reaches a preset temperature. For example, if the blower thermostat 180 is set at 65° F., the motor blower 50 and, thus, the heating element 100 may turn on if the room is at a temperature of 65° F. or less. The pump 30 may also be wired to the motor blow 50, in certain embodiments of the present invention. The thermostat 120 may be separately wired to the electrical outlet.

As previously mentioned, embodiments of the electric heating system 10 of the present invention may be used for central heating and/or space heating. In central heating embodiments, the heater core 40 may be connected to a duct. By way of example, the heater core 40 may be connected in the duct of an HVAC system. FIG. 5 illustrates connection of the heater core 40 in a duct 200, in accordance with one embodiment of the present invention. Heating medium feed 70 may provide the heating medium to the heater core 40 in the duct 200. The heating medium may be returned to the tank 20 by heating return 80. Air may be forced across the heater core 40 by the motor blower 50. More particularly, air from the blower outlet 160 may be directed across the heater core 40 in the duct 200. Heat may be transferred from the heating medium in the heater core 40 to the air from the blower outlet 160. Duct 200 may then distribute the heated air passing across the heater core 40, as needed for a particular application. For example, the duct 200 may be incorporated into an HVAC system, distributing the heated air throughout a building.

Another embodiment of the electric heating systems may be used to heat the floor in farm enclosures. By heating the ground in accordance with embodiments of the present invention, it is believed that heating costs, for example, associated with maintaining constant temperatures in the enclosure may be reduced. Non-limiting examples of faun enclosures in which embodiments of the heating systems may be used include poultry houses, such as chicken houses. In certain embodiments, the farm enclosure comprises a dirt floor. In alternative embodiments, the farm enclosure comprises a concrete floor. In an embodiment, the electric heating system may be combined with a system that burns fossil fuel to maintain the farm enclosure at the desired temperature. In an embodiment, one or more electric heating systems may be used to heat the ground in the farm enclosure. In another embodiment, one or more electric heating systems for heating the ground may be used in a combination with the previously described electric heating systems (e.g., electric heating system 10 illustrated by FIGS. 1-5) for space heating to maintain the farm enclosure at the desired temperature. The farm enclosure may be maintained at a temperature of between about 90° F. to about 100° F., for example. In an embodiment, the farm enclosure may be maintained at a temperature of about 92° F. In another embodiment, the farm enclosure may be maintained at a temperature of about 98° F.

FIG. 6 illustrates an electric heating system (e.g., ground heating system 210) in accordance with one embodiment of the present invention. In an embodiment, the ground heating system 210 may be used to heat the floor in a farm enclosure (e.g., a poultry house). As illustrated, the ground heating system 10 may include tank 20 for storing a heating medium and pump 30 for circulating the heating medium. In the illustrated embodiment, the heating medium may be heated to a desired temperature in the tank 20. Non-limiting examples of suitable heating mediums are described above. In an embodiment, the heating medium comprises antifreeze. Pump 30 circulates the heating medium in the ground heating system 210. As illustrated, the heating medium may be transmitted from the pump 30 to the tank 20 through conduit 220 with the conduit 220 fluidly connecting the pump 30 and the tank 20. As will be described in more detail below, at least a portion of the conduit 220 may be disposed within the floor of the farm enclosure. By way of example, the conduit 220 may be buried within the ground of a dirt floor. In alternate embodiments, the conduit 220 may be buried within a concrete floor. Heat loss from the underground portion of the conduit 220 should heat the ground. In this manner, the ground in the farm enclosure can be heated, reducing its heating requirements and, thus, potentially reducing fuel costs associated with heating the enclosure.

FIGS. 7-8 illustrate a configuration of the tank 20 for use with the ground heating system 210 in accordance with one embodiment of the present invention. FIG. 7 illustrates a top view of an embodiment of the tank 20. As illustrated, the top of the tank 20 may include a heating medium return 80, a thermostat 120, and a relief valve 130. FIG. 8 illustrates an end view of an embodiment of the tank 20. As illustrated, the end of the tank 20 may include a heating medium outlet 90 and a heating element 100. In accordance with present embodiments, the heating medium may be drawn from the tank 20 via the heating medium outlet 90 and returned to the tank 20, after circulation through the conduit 220, via the heating medium return 80. In embodiments, passive heat loss from the tank 20 may also serve as a space heater, heating the farm enclosure in which the ground heating system 10 is located. It should be understood that other configurations of the tank 20 (e.g., the configuration illustrated by FIG. 3) may also be suitable for use with the ground heating system 210.

The heating element 100 may be disposed through a side of the tank 20, for example. The heating element 100 may be used, for example, to heat the heating medium to a desired temperature. By way of example, the heating element 100 may heat the heating medium to a temperature of about 120° F. to about 150° F. While not illustrated, the tank 20 may further include a temperature sensor that may or may not be integrated with the heating element 100. Thermostat 120 may control the temperature of the heating medium in the tank 20, in certain embodiments. By way of example, the thermostat 120 may be set to maintain the temperature of the heating medium at a desired temperature. In this manner, the thermostat 120 may turn off the heating element 100 when the heating medium in the tank 20 reaches or exceeds the desired temperature. For example, the thermostat 120 may turn off the heating element 100 when the temperature of the heating medium reaches about 150° F. In the illustrated embodiment, the thermostat 120 is coupled to the top of the tank 20. It should be understood, however, that the thermostat 120 may be placed in any suitable location for controlling the temperature of the heating medium. The relief valve 130 may be disposed in the top of the tank 20, in accordance with embodiments of the present invention. The relief valve 130 generally may serve as an additional safety feature for the electric heating system 10. The relief valve 130 may be set to relieve excessive temperature and/or pressure inside the tank 20, for example, if it approaches the limits of the tank 20. It should be understood that the heating element 100, thermostat 120, and/or relief valve 130 for use with the ground heating system 210 may be similar to the components described above with respect to the electric heating system 10.

Any of a variety of suitable materials may be used to construct the tank 20 for use with the ground heating system 210. Examples of suitable metals include black iron, cast iron, and aluminum. Black iron generally refers to a type of metal constructed from steel that is not galvanized. Black iron tanks may be preferred in certain applications due to their improved heat absorption, for example, as compared with galvanized metals. Improved heat absorption may be preferred, in certain embodiments, to provide increased passive heat loss from the tank 20. In accordance with embodiments of the present invention, the tank 20 may constructed from a material comprising black iron and having a thickness of about ⅛ inch. In an embodiment, the tank may be insulated. The tank 20 may be of any general shape, including, for example, rectangular, square, cylindrical, oval, and a variety of other shapes that may be suitable for a particular application. In certain embodiments, the tank 20 may be a horizontal rectangular tank. Rectangular tanks may be desired in certain applications due to their ease of construction, cost, and passive heat loss, as compared to cylindrical tanks. As mentioned above, passive heat loss from the tank 20 may be desired in certain applications. The tank 20 generally should be sized based a number of factors, including the volume of the heating medium needed to provide the desired heat generation. It should be understood that the tank 20 for use with the ground heating system 210 may be similar to the tank 20 described above with respect to the electric heating system 10.

A heating medium for circulation in the ground heating system 210 may be stored in the tank 20. As illustrated by FIG. 6, the heating medium may be circulated in the system 210 through the conduit 220 in accordance with one embodiment of the present invention. A heating element 100 may be located in the tank 20 for heating the heating medium to a desired temperature. A wide variety of liquids may be suitable for use as the heating medium. Examples of suitable liquids include water, antifreeze, cooking oil, and motor oil. Combinations of suitable liquids may also be suitable. By way of example, one suitable heating medium includes a mixture of water and antifreeze. Ethylene glycol based antifreeze and propylene glycol based antifreeze should both be suitable for use in embodiments of the present invention. To reduce and/or eliminate loss of the heating medium due to evaporation, organic liquids (e.g., antifreeze) may be used in certain embodiments. Additionally, to reduce the risk of fire, antifreeze and/or water may be used in certain embodiments.

Referring again to FIG. 6, the pump 30 may circulate the heating medium in the ground heating system 210 in accordance with one embodiment of the present invention. As illustrated, the pump 30 should draw the heating medium from the tank 20 and circulate it in the system 210 through the conduit 220. The pump 30 may be connected to the tank 20 via any suitable connection. By way of example, the pump 30 may be connected to the tank 20 by a ⅝ inch heater hose. A variety of different circulating pumps may be suitable for use in the electric heating system 10, in accordance with embodiments of the present invention. An example of a suitable circulating pump is Dayton Circulating Pump SM-303-BS, available from W.W. Grainger, Inc. The pump 30 may be rated to withstand the temperatures of the circulating heating medium. For example, the pump 30 may have a maximum temperature of 230° F. or greater. It should be understood that the pump 30 for use with the ground heating system 210 may be similar to the pump 30 described above with respect to the electric heating system 10.

The ground heating system 210 illustrated by FIG. 6 further includes conduit 220. Non-limiting examples of suitable conduits 220 include those comprising black iron, cast iron, aluminum, high-density polyethylene, or polyvinyl chloride (PVC). Preferably, however, the conduit 220 may comprise a metal (e.g., black iron) having a thermal conductivity at 25° C. greater than or equal to 10 W/(m° C.). Metals may be preferred, in certain embodiments, due to their superior heat transfer. In an embodiment, the conduit 220 comprises schedule 40 pipe. In an embodiment, the conduit 220 comprise schedule 40 black iron pipe. In an embodiment, the conduit 220 comprises sections of pipe that are joined together to form conduit 220. As previously mentioned, at least a portion of the conduit 220 may be disposed in the floor of a farm enclosure. By way of example, the conduit 220 may be buried from about 1 inch to about 2 feet beneath the floor's surface, preferably from about 2 inches to about 1 foot beneath the floor's surface, and more preferably about 4 inches to about 8 inches beneath the floor's surface. For example, the conduit 220 may be buried about 2 inches, about 4 inches, about 6 inches, or about 8 inches beneath the floor's surface. In an embodiment, at least a portion of the conduit 220 is buried from about 1 foot to about 2 feet in the ground of a dirt floor of a poultry house. In an embodiment, the conduit 220 is substantially (e.g., more than 95% of its length) buried beneath the surface of the enclosure's floor.

As previously mentioned, embodiments of the present invention may include heating the floor of a farm enclosure with at least one (e.g., two, three, etc.) ground heating systems 210. FIG. 9 illustrates the use of two electric heating systems 210 to heat the floor 230 of farm enclosure 240 in accordance with one embodiment of the present invention. In an embodiment, the floor 230 comprises a dirt floor with the electric heating systems 210 used to heat the ground beneath the surface of the dirt floor. In an embodiment, the farm enclosure 240 is a poultry house (e.g., a chicken house). The poultry house may have a width of about 300 feet to about 600 feet and, more particularly, about 450 feet to about 550 feet. In an embodiment, the poultry house has a width of about 500 feet. The poultry house may have a length of about 30 feet to about 60 feet and, more particularly, about 40 feet to about 50 feet. In an embodiment, the poultry house has a length of about 43 feet.

As illustrated, each of the electric heating systems may comprise a tank 20, a pump 30, and conduit 220. At least a portion of the conduit 220 may be disposed in the floor 230 of the farm enclosure 240. By way of example, the conduit 220 may be buried from about 1 inch to about 2 feet beneath the floor's surface, preferably from about 2 inches to about 1 foot beneath the floor's surface, and more preferably about 4 inches to about 8 inches beneath the floor's surface. For example, the conduit 220 may be buried about 2 inches, about 4 inches, about 6 inches, or about 8 inches beneath the floor's surface. It may be desired, for example, to have the conduit 220 run from the outlet of the pump 220 to within the floor 230 with the remainder of the conduit 220 buried until it exits the floor 230 for return to the tank 20. In an embodiment, the portion of the conduit 220 that is exposed (e.g., not buried) may be insulated.

As illustrated by FIG. 9, the conduit 220 may be arranged in rows beneath the floor's surface. The rows of conduit 220 may be spaced apart a distance d. For example, the rows may be spaced a distance d of about 6 inches to about 48 inches, alternatively, a distance d of about 9 inches to about 24 inches, and, alternatively, a distance d of about 12, about 14, or about 18 inches. The desired spacing of the rows may be based on a number of factors including the heating need and the particular heating medium, among others.

To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention.

EXAMPLES

The following experiment was performed to evaluate the use of embodiments of the electric heating systems for heating the ground in a farm enclosure. For this experiment, an electric heating system (test system 250) was assembled that comprised a tank (not illustrated) for heating antifreeze and a pump (not illustrated) for circulating the antifreeze through the system 250. The tank included a heating element and a thermostat. The system 250 further included Schedule 40 black iron pipe 260 through which the heated antifreeze was circulated to heat the ground. The pipe 260 was arranged in the ground as illustrated by FIGS. 10 and 11. As illustrated by FIG. 10, the pipe 260 is arranged in a series of rows 270, 280, 290, 300, 310 within the ground, which are spaced apart as set forth in Table 1 below. It should be noted that the system 250 was not located in an enclosure, but rather was located in an exposed outdoor area.

TABLE 1 Row Spacing Distance Row 1 and Row 2 (D_(r1-r2)) 12 inches Row 2 and Row 3 (D_(r2-r3)) 14 inches Row 3 and Row 4 (D_(r3-r4)) 18 inches Row 4 and Row 5 (D_(r4-r5)) 18 inches

In addition, the depth that the pipe 260 was buried beneath the ground varied. In particular, the pipe 260 sloped from Row 1 (reference number 270) to Row 5 (reference number 310) as illustrated by the depth profile shown on FIG. 11. As illustrated, pipe 260 steadily sloped from a depth d1 of about 4 inches to a depth d2 of about 8 inches. In other words, Row 1 was at a depth d1 of about 4 inches, and Row 5 was at a depth d2 of about 8 inches.

For this experiment, heated antifreeze was circulated through the test system 250. Temperature readings were recorded at various points over the course of the experiment. For the ground temperature readings that were taken between rows of pipe, a temperature probe was inserted into the ground to a depth of about 5.5 inches. For the ground temperature readings that were taken at the pipe, the temperature probe was inserted to the pipe in the ground. For the ambient ground temperature, the temperature probe was inserted into the ground a distance of about 24 inches from the perimeter of the pipe 260. The results of this experiment are set forth in the table below.

TABLE 2 Reading 1 2 3 4 5 6 7 Date Mar. 5, 2010 Mar. 6, 2010 Mar. 6, 2010 Mar. 7, 2010 Mar. 7, 2010 Mar. 7, 2010 Mar. 8, 2010 Time 6:00 PM 10:00 AM 5:45 PM 7:00 AM 1:30 PM 5:30 PM 6:30 AM Circulation 0:00 16:00 23:45 37:00 43:30 47:30 60:30 Time (hr:min) Thermostat 150° F.  150° F.  150° F.  150° F.  150° F.  150° F.  150° F.  Setting Ambient 57° F. 55° F. 66° F. 46° F. 61° F. 61° F. 52° F. Temp. Ambient 50° F. 44° F. 50° F. 48° F. 52° F. 52° F. 50° F. Ground Temp. T₁ n.d. n.d n.d 90° F. 90° F. n/a 84° F. T₂ 50° F. 72° F. 80° F. 80° F. 82° F. 80° F. 80° F. T₃ n.d. n.d  98° F.¹ 90° F. 94° F. 100° F.  n/a T₄ 50° F. n.d. n.d 72° F. 72° F. 76° F. 74° F. T₅ n.d. n.d n.d. n.d n.d. n.d 86° F. T₆ 50° F. n.d. n.d 68° F. 70° F. 70° F. 72° F. T₇ n.d. n.d n.d. n.d n/d 84° F. 82° F. T₈ 50° F. 60° F. 70° F. 66° F. 68° F. 70° F. 68° F. T₉ n.d. n.d n.d.  80° F.² 80° F. 80° F. n.d. ¹This reading of 98° F. was taken at the midpoint of Row 2 (reference number 280) rather than the upper portion as illustrated by FIG. 10. ²An additional reading was taken on Row 5 (reference number 310). This reading was taken at the row's midpoint and was recorded at 80° F.

Accordingly, this example illustrates that embodiments of the electric heating systems may be used to heat the ground, indicating that the electric heating systems should be suitable for heating the ground in a farm enclosure. In addition, when comparing the temperature readings (e.g., T₂ and T₈) increased levels of ground heating was observed for the pipe spaced 12 inches and 14 inches apart as compared to the pipe spiced 18 inches apart.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims. While systems and methods are described in terms of “comprising,” “containing,” “having,” or “including” various components or steps, the systems and methods can also “consist essentially of” or “consist of” the various components and steps. 

1. An electric heating system for heating a floor of a farm enclosure, the electric heating system comprising: a tank for storing a heating medium; an electric heating element disposed in the tank for heating the heating medium in the tank; a pump for circulating the heating medium in the electric heating system; and conduit fluidly connecting the pump and the tank, wherein at least a substantial portion of the conduit is located beneath a top surface of the floor.
 2. The electric heating system of claim 1, wherein the heating medium is present in the tank, and wherein the heating medium comprises antifreeze.
 3. The electric heating system of claim 1, wherein the tank comprises black iron.
 4. The electric heating system of claim 1, further comprising a relief valve disposed in a top of the tank.
 5. The electric heating system of claim 1, further comprising a thermostat for controlling the electric heating element.
 6. The electric heating system of claim 1, wherein the conduit comprises black iron.
 7. The electric heating system of claim 1, wherein the conduit comprises a material having a thermal conductivity at 25° C. of greater than or equal to 10 W/(m° C.).
 8. The electric heating system of claim 1, wherein the substantial portion of the conduit is located a distance of about 4 inches to about 8 inches beneath the top surface of the floor.
 9. The electric heating system of claim 1, wherein the substantial portion of the conduit is arranged in rows beneath the top surface of the floor with the rows spaced a distance of about 9 inches to about 24 inches.
 10. The electric heating system of claim 1, wherein the floor is a dirt floor, and wherein the substantial portion of the conduit is buried in the ground beneath the top surface of the dirt floor.
 11. The electric heating system of claim 1, wherein the floor is a concrete floor, and wherein the substantial portion of the conduit is located within the concrete floor.
 12. The electric heating system of claim 1, wherein the farm enclosure comprises a poultry house.
 13. An electric heating system for heating a dirt floor of a poultry house, the electric heating system comprising: a tank containing a heating medium comprising antifreeze; an electric heating element disposed in the tank for heating the heating medium in the tank; a pump for circulating the heating medium in the electric heating system; and conduit fluidly connecting the pump and the tank, wherein the conduit comprises a buried portion that is in ground beneath a top surface of the dirt floor, wherein the conduit comprises a material having a thermal conductivity at 25° C. of greater than or equal to 10 W/(m° C.).
 14. The electric heating system of claim 13, wherein the material comprises black iron.
 15. The electric heating system of claim 13, wherein the material comprises a metal.
 16. The electric heating system of claim 13, wherein the buried portion of the conduit is located a distance of about 4 inches to about 8 inches beneath the top surface of the floor.
 17. The electric heating system of claim 13, wherein the buried portion of the conduit is arranged in rows beneath the top surface of the floor with the rows spaced a distance of about 9 inches to about 24 inches.
 18. The electric heating system of claim 13, wherein the farm enclosure comprises a chicken house.
 19. A method of heating a floor of a farm enclosure comprising: heating a liquid in a tank with an electric heating element, wherein the liquid comprises antifreeze; circulating the liquid beneath a top surface of the floor such that the liquid heats the floor; and returning the liquid to the tank.
 20. The method of claim 19 wherein the floor is a dirt floor, and wherein the circulating comprises circulating the liquid in ground beneath the top surface of the dirt floor. 